Method of welding bearing pins to legs of drill bits



April 3', 192 8.

H. H. HOLDAWAY 7 METHOD OF WELDING BEARING PINS TO LEGS 0F DRILL BITS Filed June 22, 1926 Patented Apr. 3, 1 928 HALL HOLIDAWAY, Q13 LONG BEACH, CALEOENIA.

ran'rnon or WELDING nnenrne PINS To LEGS or paint nrrs.

Application filed June 22, 1926. Serial No. 117,670.

In Patent No. 1,569,280, granted January 12, 1920, is disclosed an improved type. of disc bit comprising a shankwhich downwardly terminates in legs, the relatively inaccessible inner faces of these legs being provided with bearing pins or trunnions for cutting discs,-suitable bushings being secured upon said pinsor trunnions in a manner which is immaterial to my present invention; and it is a primary object of thisinvention to improve upon the construction and method described or implied in the above mentioned patent,--the corresponding bearing pins herein described being separately I, forged,

rately shaped to cooperate in the provision of an annular cavity favorable to welding operations by which said pins may be securely disposed at right angles to the inner faces of said legs.

It is an object (if this invention to provide an improved method of securing a pin at a predetermined angle to a relatively inaccessible surface of a main member, such as a leg integral with a disc drill bit shank or body,-welding operations being executed from the side of a main member other than that from which said pin projects; and the herein described method has the notable advantages, among others, (1) that it simplifies the operations requisite tothe forging of a main member such as a drill bit shank provided with separate legs, (2) that it permits accurate work, such as boring and. thread-cutting operations, to be expeditiously done upon separatev ins before they are attached to a shank; (3% that it greatly facilitates the replacement of pinsin case of breakage, (4) that it assures a reliable weld, joining a pin to a main member, and (5) that it permits welding operations to be executed from a side opposite to that from which a pin is to project. I

Other objects of my invention, including the use of a pin having a tapered body,--an

. intermediate portion of said'pin having a maximum diameter adapting it. to interfit within the narrowest portion of a 'non-uni form bore provided in a leg of a drill bit,

and the body of said pin and said leg being respectively so cut-away as to provide an annular space favorably shaped for efficient welding,-may be best appreciated from the following description of an illustrative embodiment of my invention, taken in connecand said pins and legs being sepadirected. The cylindrical shank 11 bit is shown as connected with a coupling or sion '24:, adjacent tion with the appended claims, and the accompanying drawings, in which Fig. 1 is a perspective view of a drill bit whose le s are provided with pins inserted in acoor ance with my present invention.

Fig. 2 is a bottom plan view, upon an enlarged scale, taken as indicated by the arrow 2 of Fig. 1 with parts broken away.

Fig. 3is a side elevational view on a somewhat enlarged scale, which ma be regarded as taken from the direction in icate'd'by the arrow 3 of Fig. 1, during welding operations of the, general character hereinafter described.

Fi 4 is a View taken substantially as in- Referring to the details of that specific embodiment of my invention chosen for purposes of illustration, Figs. 1 and 2 have reference more particularly to a finished product whereas Figs. 3 and 1 illustrate welding operations toward which claims of the present applicatibn are more particularly of a drill enlargement or sub 12, comprising a socalled pin 13, of a usual character,-legs 14 and 15 at the lower end of said shank being respectively provided with pins 16, which directly or indirectly support cutting discs 17; and, in the form of my invention selected for illustration, each of the pins 16 may comprise not only a threaded portion 18, adapted to carry a bearing bushing 19, but also a tapered body 20, shown as corresponding in length with the thickness of the leg through which it extends,--said le being provided with an outwardly expan ing bore 21, narrowest in a region 22, in proximity to inner face 23 of said leg and adapted to interfit; in this region, with an intermediate expana fiat face or shoulder 25 upon the body 20,--said shoulder being (an I gageable by a, corresponding annular surface of the bearing bushing 19, or its equivalent and in the same plane wlth the mentioned inner face 23 of a leg.

Although details of construction of the bearing bushing 19, preferably formed of an exceptionally hard material, may be regarded as immatenal to my present invention, I

mention that this bushing is shown as provided with a enlargement at 26, favorable to the retention of a cutting disc 17 thereon, and that" the unscrewing of said bearing bushing from a pin 18 may be prevented by means such as a 27, adapted to interfit within notches 2 8 and 29 respectively provided in said bushing and said pin,this key being in turn, retained by means such as'a screw 30, shown as extending through a central bore 31 in the pin 16, and the head of this pin being preferably countersunk in a central depression 32, in such manner as to obviate Wear thereon.

My present invention being directed more particularly to a preferred method of'secure ing an accurately threaded or other pin, such as the pin 16, at a predetermined angle (as at a right angle) to a comparatively inaccessible surface, such as the surface 23 of a main I member such asone of the legs 14, l5,refer- I walls (either ring now more particularly to Figs. 3 and 4, I comment upon the very severe strains to which a pin 16 may be subjected, byireason of the enormous weight of a rill pipe extending thereabovef and upon the corresponding importance of providing means for the very secure retention of a pin, of suitable hard metal,zwithin a leg, alsofor'med of hard metal; and also upon the advantages in so securing pins, of the general character referredto, as to permit of their replacement in case of damage thereto.

In this connectiom'it will be appreciated that although the legs 14 and 15 are shown as slightly offset in a manner favorable to the cutting of a hole exceeding in diameter the extreme diameter of the respective discs 17 the distance between the inner faces 23, 23' not favorable to the execution of welding operations in the space between said legs;

and I accordingly so dispose the flaring surface 21 of the mentioned bore, provided in each leg, and an op ositely inclined or ta pered surface 33 of t e outwardly diminishmg body 20 of each pin, as to provide an annu ar' space 34, around each pin body, favorable to the reception of a considerable quantity of initially molten metal, for a bending effect; and at least one of the mentioned the outwardly flared wall of" the bore 21 or the outwardly tapering surface 33 of the pin body 20) may be'rendered concave in profile, as at 35, near the bottom thereof,the angle between the mentioned walls and the concave configuration referred to being favorable to the insertion of a me-- tallic electrode (or of another body of metal to be melted for a welding effect) at a considerable angle relativelyto the surface u on which the molten metal is intended to be isposed.

For example, during the beginning of welding operations, assuming a pin to hemserted and held in the relative position illustrated in Figs. 2, 3 4 by a suitably tight fit or a drive fit inthe mentioned region 24,) the leg or other main transversely extending key i mentioned electrode acent wall.

require optionally employed for a centering effect of several hundred complete embodiment of my invention,

and 4 (as by a drive fit or with a source of current (in the case of electric welding) as to constitute the same an electrode, and assuming a cooperating electrode 36 to be formed of the metal by which said main member and pin are to be united (all parts being advantageously made of, for example, a chrome-nickelsteel) said lastmay advantageously be shifted between and beyond positions such as those illustrated in Figs. 3 and 4,forming in'all cases a considerable angle with the adprevent undue spreading of the arc, concentrating the heating effect at first in the bottom of-the annular passage 34, and gradually filling the same, under advantageous conditions, with a body very effectively bonded to both of'the adjacent walls.

I' find that a welded joint formed in the de-' scribed manner isentirely permanent; but that it is nevertheless such as to permit a broken pin to be drilled out, as occasion ma (the mentioned bore 31 being then during drilling operations) and the insertion of a new pin by steps of thegeneral character described. a

The general mode of use of these drill bits being well understood, I may emphasize, in conclusion, the fact that large bits embodying the invention set forth in my mentioned patent are currently made and sold at a cost dollars a piece, whereas the insertion or replacement of a threaded pin in the general manner described, whether the welding is done by electrical means or by the use of an oxygen-acetylene flame, or by a so-called thermite process, or otherwise, need not cost more than (say) fifteen to thirty dollars equipment to be at hand, such insertion or replacement may easil be effected, by w0rkmen of ordinary skill: at any shop in the region where the drilling is in pro ess.

Although I have herein descri d a single it should be understood not only that various features thereof might be independently employe but also that numerous modifications might be made by those skilled in the art to which this case departure from the spirit and scopev of my in the follow ng claims. I claim as my invention:

37 of deposited metal and assuming suitable simple relates, without the slightest By proceeding in this way, I 1

1. A method of securing inwardly projecting bearing pins to the relatively inaccesslble inner surfaces of legs integral with shanks of drilling bits viding said legs respectively with outwardly 2125 which comprises: pro- Y expanding openings extending therethrough,

each op 'ening being narrowest in a region in proxim ty to an inner surface on leg; providing each pin with a body which tapers uniformly from an intermediate region which has a maximum'diameter adapting it to interfit within the mentioned narrowest portion of an opening through a leg; and securing said pins insaid legs by depositing molten metal in resultant annular spaces between said pins and said legs.

2. A method of securing inwardly projecting bearing pins to the relatively inaccessible inner surfaces of legs integral with shanks of drilling bits which comprises:

- providing said legs respectively with out- Wardly expanding openings extending therethrough, each opening beingnarrowest in a region in proximity to an inner surface of a leg; providing each pin with a body which tapers uniformly from an intermediate reion which has a maximum diameter adaptlng it to interfit within the mentioned narrowest portion of an opening through a leg;

and securing said pins on said legs by de-' positing molten metal in resultant annular spaces between said pins and said legs,the inclinations of oppositely inclined walls of said pins and said legs'being such as to permit an electrode inserted therebetween to contact with one of said walls at a considerable angle.

3. In the attachment of a pin to a main member having a relatively inaccessible inner surface and a more accessible outer surface, a method which comprises: providing said pin with a uniformly tapered body substantially corresponding in length with the thickness of said main member; providing said main member with a bore inwardly diminishing to a diameter corresponding to the maxlmum tapered body; inserting said body within said bore; and forming a joint between said body and said member by the deposition of molten metal within a resultant annular diameter of said adapts it tointerfit within the narrowest portion of the bore in said mam member, one of the adjacent walls being so concaved as to permit the insertion of an electrode at a comparatively high angle relatively there- .to.

In testimony whereof, I have hereunto set my hand "at Los Angeles, California, this 16th day of June, 1926.

HALL H. 'HOLDAWAY. 

